allow pasting attachments from keyboard

Closes #55

android/app/src/main/AndroidManifest.xml

@@ -51,6 +51,16 @@
         <meta-data
             android:name="flutterEmbedding"
             android:value="2" />
+        <!-- Needed by pasteboard, for pasting files from the clipboard -->
+        <provider
+            android:name="androidx.core.content.FileProvider"
+            android:authorities="${applicationId}.provider"
+            android:exported="false"
+            android:grantUriPermissions="true">
+            <meta-data
+                android:name="android.support.FILE_PROVIDER_PATHS"
+                android:resource="@xml/provider_paths" />
+        </provider>
     </application>
     <!-- Required to query activities that can process text, see:
          https://developer.android.com/training/package-visibility and

android/app/src/main/res/xml/provider_paths.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<paths xmlns:android="http://schemas.android.com/apk/res/android">
+    <external-path
+        name="external_files"
+        path="." />
+</paths>

lib/widgets/composer/composer.dart

@@ -18,6 +18,10 @@ import "package:nexus/controllers/power_level.dart";
 import "package:nexus/models/content/message.dart";
 import "package:nexus/models/relation_type.dart";
 import "package:nexus/widgets/composer/overlays/tagger_overlay.dart";
+import "package:nexus/widgets/composer/paste_files_action.dart";
+import "package:pasteboard/pasteboard.dart";
+import "package:path/path.dart";
+import "package:path_provider/path_provider.dart";
 import "package:nexus/widgets/composer/relation_preview.dart";
 import "package:nexus/main.dart";
 
@@ -100,6 +104,46 @@ class const Composer(
       }
     }
 
+    /// Attaches [bytes] as a file called [filename], e.g. for pasted images.
+    Future<void> attachBytes(Uint8List bytes, String filename) async {
+      // A new directory each time, so files with the same name don't clash
+      final directory = await (await getTemporaryDirectory()).createTemp(
+        "attachment",
+      );
+      final file = await File(join(directory.path, filename))
+          .writeAsBytes(bytes);
+
+      await ref
+          .read(AttachmentController.provider(roomId).notifier)
+          .add(.new(file.path));
+    }
+
+    /// Attaches the first file on the clipboard, or the image on it if there
+    /// are no files. Returns whether there was either, so that text can be
+    /// pasted otherwise.
+    Future<bool> pasteFiles() async {
+      // Only one attachment is supported at a time
+      if (attachment != null) return false;
+
+      // Failing to read the clipboard counts as it being empty, so that text
+      // can still be pasted
+      final files = await Pasteboard.files().onError((_, _) => const []);
+      if (files.firstOrNull case final path?) {
+        ref
+            .read(AttachmentController.provider(roomId).notifier)
+            .add(XFile(path))
+            .onError(showError);
+        return true;
+      }
+
+      if (await Pasteboard.image.onError((_, _) => null) case final image?) {
+        attachBytes(image, "image.png").onError(showError);
+        return true;
+      }
+
+      return false;
+    }
+
     void send() {
       if (controller.value.text.isEmpty && attachment == null ||
           attachment != null && attachment.$2 == null) {
@@ -257,21 +301,65 @@ class const Composer(
 
                                     return KeyEventResult.ignored;
                                   },
-                                  child: TextField(
+                                  // Overrides the keyboard shortcut for pasting
-                                    maxLines: 12,
+                                  child: Actions(
-                                    minLines: 1,
+                                    actions: {
-                                    textCapitalization: .sentences,
+                                      PasteTextIntent: PasteFilesAction(
-                                    autofocus:
+                                        pasteFiles,
-                                        (Platform.isLinux ||
+                                      ),
-                                        Platform.isMacOS ||
+                                    },
-                                        Platform.isWindows),
+                                    child: TextField(
-                                    decoration: .new(
+                                      maxLines: 12,
-                                      hintText: "Your message here...",
+                                      minLines: 1,
-                                      border: .none,
+                                      textCapitalization: .sentences,
+                                      autofocus:
+                                          (Platform.isLinux ||
+                                          Platform.isMacOS ||
+                                          Platform.isWindows),
+                                      decoration: .new(
+                                        hintText: "Your message here...",
+                                        border: .none,
+                                      ),
+                                      controller: controller,
+                                      key: key,
+                                      focusNode: node,
+                                      // The toolbar's paste button doesn't use the shortcut's action, so replace it too
+                                      contextMenuBuilder: (_, editableText) =>
+                                          AdaptiveTextSelectionToolbar.buttonItems(
+                                            anchors:
+                                                editableText.contextMenuAnchors,
+                                            buttonItems: editableText
+                                                .contextMenuButtonItems
+                                                .map(
+                                                  (item) => item.type == .paste
+                                                      ? item.copyWith(
+                                                          onPressed: () async {
+                                                            editableText
+                                                                .hideToolbar();
+                                                            if (!await pasteFiles()) {
+                                                              item.onPressed
+                                                                  ?.call();
+                                                            }
+                                                          },
+                                                        )
+                                                      : item,
+                                                )
+                                                .toList(),
+                                          ),
+                                      // Images pasted from Android keyboards' clipboards are inserted as content
+                                      contentInsertionConfiguration: .new(
+                                        onContentInserted: (content) {
+                                          if (attachment != null) return;
+
+                                          if (content.data case final data?) {
+                                            attachBytes(
+                                              data,
+                                              "image.${content.mimeType.split("/").last}",
+                                            ).onError(showError);
+                                          }
+                                        },
+                                      ),
                                     ),
-                                    controller: controller,
-                                    key: key,
-                                    focusNode: node,
                                   ),
                                 ),
                               ),

lib/widgets/composer/paste_files_action.dart

@@ -0,0 +1,12 @@
+import "package:material_ui/material_ui.dart";
+
+/// Overrides a text field's paste, to paste files and images with
+/// [pasteFiles], falling back to pasting text if it returns false.
+class PasteFilesAction(final Future<bool> Function() pasteFiles)
+    extends Action<PasteTextIntent> {
+  @override
+  Future<void> invoke(PasteTextIntent intent) async {
+    // callingAction is the text field's own paste action, which this overrides
+    if (!await pasteFiles()) callingAction?.invoke(intent);
+  }
+}

linux/flutter/generated_plugin_registrant.cc

@@ -11,6 +11,7 @@
 #include <file_selector_linux/file_selector_plugin.h>
 #include <media_kit_libs_linux/media_kit_libs_linux_plugin.h>
 #include <media_kit_video/media_kit_video_plugin.h>
+#include <pasteboard/pasteboard_plugin.h>
 #include <screen_retriever_linux/screen_retriever_linux_plugin.h>
 #include <url_launcher_linux/url_launcher_plugin.h>
 #include <webcrypto/webcrypto_plugin.h>
@@ -32,6 +33,9 @@ void fl_register_plugins(FlPluginRegistry* registry) {
   g_autoptr(FlPluginRegistrar) media_kit_video_registrar =
       fl_plugin_registry_get_registrar_for_plugin(registry, "MediaKitVideoPlugin");
   media_kit_video_plugin_register_with_registrar(media_kit_video_registrar);
+  g_autoptr(FlPluginRegistrar) pasteboard_registrar =
+      fl_plugin_registry_get_registrar_for_plugin(registry, "PasteboardPlugin");
+  pasteboard_plugin_register_with_registrar(pasteboard_registrar);
   g_autoptr(FlPluginRegistrar) screen_retriever_linux_registrar =
       fl_plugin_registry_get_registrar_for_plugin(registry, "ScreenRetrieverLinuxPlugin");
   screen_retriever_linux_plugin_register_with_registrar(screen_retriever_linux_registrar);

linux/flutter/generated_plugins.cmake

@@ -8,6 +8,7 @@ list(APPEND FLUTTER_PLUGIN_LIST
   file_selector_linux
   media_kit_libs_linux
   media_kit_video
+  pasteboard
   screen_retriever_linux
   url_launcher_linux
   webcrypto

linux/nix/devshell.nix

@@ -8,7 +8,10 @@ let
       "36.0.0"
     ];
     cmakeVersions = [ "3.22.1" ];
-    platformVersions = [ "36" ];
+    platformVersions = [
+      "34"
+      "36"
+    ];
     abiVersions = [
       "armeabi-v7a"
       "arm64-v8a"

macos/Flutter/GeneratedPluginRegistrant.swift

@@ -12,6 +12,7 @@ import flutter_local_notifications
 import media_kit_libs_macos_video
 import media_kit_video
 import package_info_plus
+import pasteboard
 import screen_retriever_macos
 import shared_preferences_foundation
 import url_launcher_macos
@@ -27,6 +28,7 @@ func RegisterGeneratedPlugins(registry: FlutterPluginRegistry) {
   MediaKitLibsMacosVideoPlugin.register(with: registry.registrar(forPlugin: "MediaKitLibsMacosVideoPlugin"))
   MediaKitVideoPlugin.register(with: registry.registrar(forPlugin: "MediaKitVideoPlugin"))
   FPPPackageInfoPlusPlugin.register(with: registry.registrar(forPlugin: "FPPPackageInfoPlusPlugin"))
+  PasteboardPlugin.register(with: registry.registrar(forPlugin: "PasteboardPlugin"))
   ScreenRetrieverMacosPlugin.register(with: registry.registrar(forPlugin: "ScreenRetrieverMacosPlugin"))
   SharedPreferencesPlugin.register(with: registry.registrar(forPlugin: "SharedPreferencesPlugin"))
   UrlLauncherPlugin.register(with: registry.registrar(forPlugin: "UrlLauncherPlugin"))

pubspec.lock

@@ -1047,6 +1047,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "4.1.0"
+  pasteboard:
+    dependency: "direct main"
+    description:
+      name: pasteboard
+      sha256: fedbe8da188d2f713aa8b01260737342e6e1087534a3ab26e1a719f8d3e8f32f
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.5.0"
   path:
     dependency: "direct main"
     description:

pubspec.yaml

@@ -97,6 +97,7 @@ dependencies:
         git:
             url: https://github.com/Henry-Hiles/xdg_desktop_portal.dart
             ref: quad/nexus
+    pasteboard: 0.5.0
 
 dev_dependencies:
     build_runner: 2.16.2

windows/flutter/generated_plugin_registrant.cc

@@ -11,6 +11,7 @@
 #include <file_selector_windows/file_selector_windows.h>
 #include <media_kit_libs_windows_video/media_kit_libs_windows_video_plugin_c_api.h>
 #include <media_kit_video/media_kit_video_plugin_c_api.h>
+#include <pasteboard/pasteboard_plugin.h>
 #include <screen_retriever_windows/screen_retriever_windows_plugin_c_api.h>
 #include <url_launcher_windows/url_launcher_windows.h>
 #include <webcrypto/webcrypto_plugin.h>
@@ -27,6 +28,8 @@ void RegisterPlugins(flutter::PluginRegistry* registry) {
       registry->GetRegistrarForPlugin("MediaKitLibsWindowsVideoPluginCApi"));
   MediaKitVideoPluginCApiRegisterWithRegistrar(
       registry->GetRegistrarForPlugin("MediaKitVideoPluginCApi"));
+  PasteboardPluginRegisterWithRegistrar(
+      registry->GetRegistrarForPlugin("PasteboardPlugin"));
   ScreenRetrieverWindowsPluginCApiRegisterWithRegistrar(
       registry->GetRegistrarForPlugin("ScreenRetrieverWindowsPluginCApi"));
   UrlLauncherWindowsRegisterWithRegistrar(

windows/flutter/generated_plugins.cmake

@@ -8,6 +8,7 @@ list(APPEND FLUTTER_PLUGIN_LIST
   file_selector_windows
   media_kit_libs_windows_video
   media_kit_video
+  pasteboard
   screen_retriever_windows
   url_launcher_windows
   webcrypto